A fix is available
APAR status
Closed as program error.
Error description
DB2DDF DB2HIGHPERFDBAT defect pi31597 dpi31597 If High Performance DBATs are being used, it is possible that locks acquired with duration allocation will not be released when the requester disconnects. A new connection may be assigned to this DBAT. This new connection, which can be from an application unrelated to the first use of the High Performance DBAT, may appear to inherit the locks from the earlier connection.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All Distributed Data Facility (DDF) users * * who are using, or plan to use, * * High Performance DBAT support. That is, * * users which operate DDF with option * * PKGREL(BNDOPT). * **************************************************************** * PROBLEM DESCRIPTION: Threads unexpectedly hold package and * * table space intent locks. * **************************************************************** * RECOMMENDATION: * **************************************************************** DB2 10 for z/OS introduced a new DDF server thread processing mode called High Performance DBATs. With APAR PI20352, DB2 was changed to address situations where the activation of High Performance DBATs could lead to an increase in the CPU consumed to process distributed client requests. The change enabled the pooling of high performance DBATs when the requesting client connection (using the DBAT) was terminated. When a High Performance DBAT is allowed to be pooled, as a result of the PI20352 change, any client connection could potentially be serviced by this DBAT - even a client connection that was not enabled to utilize a High Performance DBAT. This results in application connections having (or inheriting) unexpected "package allocation" and/or "table space intent" locks from other unrelated applications.
Problem conclusion
DB2 has been changed to restore the prior (to APAR PI20352) PKGREL(BNDOPT) behavior. But in order to accommodate client environments where any connection can utilize High Performance DBATs, DB2 has also been changed to support a new BNDPOOL High Performance DBAT processing option value via the -MODIFY DDF PKGREL(BNDPOOL) command. When DDF has been modified to run with a PKGREL value of BNDOPT, DDF will (again) terminate a High Performance DBAT when the client connection terminates. When DDF has been modified to run with a (new) PKGREL value of BNDPOOL, DDF will pool a high performance DBAT when the client connection terminates. Thus, for those customers who configure client environments with or without the ability to use High Performance DBATs, a PKGREL value of BNDOPT may be the preferred value. For those customers who just configure DDF server resources to allow any client connection to use High Performance DBATs, a PKGREL value of BNDPOOL may be the preferred value. Documentation changes are required to describe the function provided by this APAR. Changes to the DB2 10 and DB2 11 Messages Manuals. --------------------------------------------------------------- The explanation text of messages DSNL004I and DSNL302I is changed: * The description of the BNDOPT value of the PKGREL DDF processing option is changed to have an additional paragraph as follows: When a connection which has used a high performance DBAT terminates, the high performance DBAT will also be deallocated. * A description of a new PKGREL DDF processing option value, BNDPOOL, is added as follows: BNDPOOL DDF processing for the BNDPOOL option value will be the same as the BNDOPT option value with the following exception: when a connection which has used a high performance DBAT terminates, the high performance DBAT will be pooled. The pooled DBAT can then be used by any other connection which presents a request to this DB2 subsystem. Changes to the DB2 10 and DB2 11 Command Reference manuals. --------------------------------------------------------------- The description of the PKGREL option of the MODIFY DDF command is replaced with the following: PKGREL Specifies whether DB2 honors the bind options of packages that are used for remote client processing. The PKGREL option also controls the disposition of high performance DBATs when a client connection which has used a high performance DBAT has terminated. BNDOPT The rules of the RELEASE bind option that was specified when the package was bound are applied to any package that is used for remote client processing. The high performance DBAT used by a terminating client connection will be deallocated. BNDOPT is the default value of the MODIFY DDF PKGREL command. BNDPOOL The rules of the RELEASE bind option that was specified when the package was bound are applied to any package that is used for remote client processing. The high performance DBAT used by terminating a client connection will be pooled. COMMIT The rules of the RELEASE(COMMIT) bind option are applied to any package that is used for remote client processing. COMMIT is the default value when the CMTSTAT subsystem parameter is set to ACTIVE. If the MODIFY DDF PKGREL command had never been issued, then COMMIT is the default value. No high performance DBATs exist while the PKGREL option is set to COMMIT. The usages notes of the -MODIFY DDF command is changed as follows: When to use PKGREL options: You can specify that DDF uses the PKGREL(BNDOPT) or PKGREL(BNDPOOL) option during normal production operating hours. For environments where client configurations control the use of packages which were bound with the RELEASE(DEALLOCATE) bind option, BNDOPT will be the preferred value of the PKGREL option. For environments where any client is capable of using packages bound with the RELEASE(DEALLOCATE) bind option, BNDPOOL will be the preferred value of the PKGREL option. Either option value offers improved performance by reducing the amount of CPU costs for allocating and deallocating packages. However, packages that run under the rules of the RELEASE(DEALLOCATE) bind option are likely to remain allocated and prevent maintenance activities such as objects modifications and bind operations. Consequently, you can use the PKGREL(COMMIT) option during routine and emergency maintenance periods.
Temporary fix
Comments
APAR Information
APAR number
PI31597
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
A10
Status
CLOSED PER
PE
YesPE
HIPER
NoHIPER
Special Attention
YesSpecatt / New Function / Xsystem
Submitted date
2014-12-15
Closed date
2015-03-02
Last modified date
2015-05-12
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI25563 UI25564
Modules/Macros
DSNGEFLC DSNGEPLC DSNLEDDA DSNLQCTL DSNLQDIS DSNLSSST DSNLTDDF DSNLTMDF DSNLXPRS DSN9SCNA
SC19405400 | SC19297200 | GC19406200 | GC19297900 |
Fix information
Fixed component name
DB2 OS/390 & Z/
Fixed component ID
5740XYR00
Applicable component levels
Fix is available
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Document Information
Modified date:
06 May 2020